最佳实践

多索引自适应选择支持，举例如下：

create table t1(c1 int, c2 int, c3 int, c4 varchar(32), c5 text);
create index t1_idx2 on t1(c1,c2,c3,c4);
create index t1_idx1 on t1(c1,c2,c3);

insert into t1( c1, c2, c3, c4, c5) SELECT (random()*(2*10^9))::integer , (random()*(2*10^9))::integer,  (random()*(2*10^9))::integer, (random()*(2*10^9))::integer,  repeat('abc', i%10) ::text from generate_series(1,1000000) i;
insert into t1( c1, c2, c3, c4, c5) SELECT (random()*1)::integer, (random()*1)::integer, (random()*1)::integer, (random()*(2*10^9))::integer, repeat('abc', i%10) ::text from generate_series(1,1000000) i;

性能对比：

随机参数：c1~ random(1, 20); c2~ random(1, 20); c3~ random(1, 20); c4 ~ random(2, 10000)

线程数50，客户端50，执行时长60s

方法	语句	tps
gplan	`prepare k as select * from t1 where c1=$1 and c2=$2 and c3=$3 and c4=$4;`	35126
cplan	`prepare k as select /+ use_cplan / * from t1 where c1=$1 and c2=$2 and c3=$3 and c4=$4;`	75817
gplan选择	`prepare k as select /+ choose_adaptive_gplan / * from t1 where c1=$1 and c2=$2 and c3=$3 and c4=$4;`	175681